1. Field of the Invention
The present invention relates to a plug, particularly for connecting a musical instrument, a microphone, or the like, to an amplifier, a recording device, or the like. The plug includes a central rod-shaped conductor which at one end thereof has a mushroom-shaped portion, a sleeve or electrically conductive material surrounding the rod-shaped conductor at a radial distance, and insulating material which separates the rod-shaped conductor from the sleeve.
2. Description of the Related Art
Plugs of the above-described type have been used successfully for a long period of time in musical instruments, in Hi-Fi units, particularly for connecting the units to headsets, and in many other applications.
Musical instruments, or more precisely the sound-pickups thereof, are usually connected by means of a cable to the respective amplifier, mixer unit, recording unit or sound processing device.
The cables include plugs which are inserted into sockets of the device provided for this purpose. In principle, there are plugs in which the cable extends essentially in the direction of the plug axis away from the device, and plugs in which the cable extends essentially at a right angle to the plug axis. The actual plug itself is of identical construction in each case, so that a cable with one of the two types of plugs is used depending on the specific situation and the desire of the player of the instrument.
For various reasons, the cables have in recent times increasingly been replaced by wireless transmission. This means that a miniaturized transmitter is mounted at the device and that a corresponding receiver is provided at the location of sound processing, amplification, or etc., for each instrument whose signals are transmitted by radio. For simplicity"" sake, for connecting the musical instrument to the transmitter, the sockets provided at the musical instrument are used, so that the plugs provided at the transmitters are of the same construction as the plugs previously used at cables.
However, contrary to the transmission of signals by means of cables, in the case of the radio transmitter the orientation of the radio relative to the longitudinal axis of the plug is a critical variable. For example, if in an extremely flat electrical guitar the socket is arranged in such a way that its axis is located in the middle plane of the guitar, the transmitter should also be arranged relative to the plug in such a way that it is located essentially in the continuation of this axis, since otherwise there is the danger that the transmitter will be pulled out of the socket by the use of the instrument.
In contrast, a transmitter which is used on a guitar whose socket is located on the guitar surface and whose axis therefore extends at a right angle relative to the plane of the guitar, should also be arranged so as to extend at a right angle to the plug axis, so that the transmitter does not protrude above the surface of the guitar and impair the playing of the instrument.
Of course, there are a plurality of other applications including those in which signals are once again conducted through a cable; however, the significance of the invention shall be explained with the aid of the examples mentioned above.
In order to meet the above requirement, in the past two types of amplifiers were required to be available. These two types include those which essentially are mounted and arranged in the direction of the plug axis and, in the alternative, those which are mounted essentially in a plane at a right angle to the plug axis which take only little room in the direction of the plug axis.
The plugs themselves are constructed so as to be symmetrical with respect to rotation about the plug axis, which in the inserted state of course coincides with the socket axis, so that the plug is rotatable in the socket. The plug is constructed with a rod-shaped central member which is at one end thereof provided with a mushroom-shaped portion, wherein the rod-shaped member is surrounded over a major portion of its axial length by an electrically conductive cylindrical sleeve which is electrically insulated from the rod-shaped member, wherein the sleeve ends at a distance from the mushroom-shaped portion. This makes a two-pole contact and the mushroom-shaped configuration of one of the contacts ensures that the plug can be secured in the socket in a frictionally engaging manner (resilient tongue, etc.).
Three-pole embodiments are also available, however, these are usually not used for signal transmission from musical instruments, but for example for transmitting stereo signals (headsets, etc.). These plugs are constructed completely analogously to the above-mentioned plugs and, in addition to the rod-shaped member and the cylindrical outer sleeve, these plugs have a tubular central conductor which over only an axial portion between the outer sleeve and the mushroom-shaped portion, has an outwardly exposed surface which can be contacted.
In view of the prior art discussed above, it is the primary object of the present invention to provide a plug in which different constructions of transmitters, filters or the like are not necessary, or which makes it possible that a cable extending from the plug can always extend at an angle which is optimal for the specific type of application.
In accordance with the present invention, the rod-shaped central member has at its end facing away from the mushroom-shaped end of the plug a cylindrical transverse rod which forms a T-shape relative to the rod-shaped member, wherein the transverse rod has two rod portions having different diameters extending from the center axis of the rod-shaped member, wherein the rod-shaped member and the two rod portions are electrically conductively connected. The outer electrically conductive sleeve is connected in an electrically conductive manner to a surface portion of the sleeve which at least partially surrounds the thinner rod portion at a distance and is electrically insulated therefrom.
As a result of the configuration according to the present invention, it is possible to mount the plug with the T-shaped member rotatably in a bearing, wherein the T-shaped member simultaneously serves as the electrical contact. The bearing can be provided as desired in a transmitting unit, a cable shoe, an electrical filter unit, or any other electronic structural unit. Consequently, the structural component, in which the plug is pivotally mounted, can be arranged at any desired angle when the plug is inserted into the socket, wherein the T-shaped portion serves for the electrical contact of the inner conductor, on the one hand, and the electrical contact of the outer conductor, usually ground, on the other hand.